The field of art to which this invention pertains is thickeners for aqueous coating compositions.
Coating compositions based on aqueous dispersions of synthetic resins have been known for a considerable number of years. It is well known to those skilled in the art of formulating paints that various thickening agents can be added to the paint formulations to obtain desirable rheology properties. Compositions which have been used as thickening agents include starch, methyl cellulose, hydroxyethyl cellulose, treated bentonites, hydroxalkyl guar, and the like.
U.S. Pat. No.3,700,612 describes coating compositions made from aqueous dispersions of film-forming resins which contain, as thickeners, hydroxyalkyl ethers of polygalactomannans. According to the patent, coating compositions which contain hydroxyalkyl ethers of polygalactomannans can be applied without sagging or balling and exhibit excellent flow and leveling characteristics.
Our U.S. Pat. No. 4,870,167, describes hydrophobically modified nonionic polygalactomannan ethers and their use in water borne coatings.
European patent application No. 323,627 discloses water paints formulated with polygalactomannans modified with hydrophilic and hydrophobic groups.